1. Field of the Invention
The present invention relates to a technology that, without the sequence of data frames and data frame loss measurement frames being switched from a normal sequence to an incorrect sequence, accurately measures data frame loss between transmitting and receiving devices that have a plurality of transmitting and receiving links.
2. Description of Related Art
A technology is known that measures data frame loss using Ethernet (registered trademark) OAM (Operation Administration and Maintenance) or MPLS-TP (Multi-Protocol Label Switching-Transport Profile).
A technology that measures data frame loss between a pair of communication devices is disclosed in ITU-T Recommendation Y.1731. The pair of communication devices are MEP (Maintenance Entity Group End Point) devices. The MEP on the transmitting side measures the number of transmitted data frames, and writes this number in a data frame loss measurement frame. The MEP on the receiving side measures the number of received data frames and writes this number in the data frame loss measurement frame. By then subtracting the number of received data frames from the number of transmitted data frames, the data frame loss between the MEP on the transmitting side and the MEP on the receiving side is measured. However, when a relay device is installed between the pair of communication devices, then, when viewed from this relay device, it is not possible to determine whether the data frame loss occurred on the transmitting side or on the receiving side.
In Japanese Unexamined Patent Application, First Publication, (JP-A) No. 2008-244870, a technology is disclosed that, when a relay device is installed between a pair of communication devices, determines whether a data frame loss has occurred on the transmitting side or on the receiving side as viewed from this relay device. The relay device is an MIP (Maintenance Entity Group Intermediate Point) device. The MEP on the transmitting side measures the number of data frames being transmitted and writes this number in a data frame loss measurement frame. The MIP measures the number of received data frames and, in addition to writing this number in the data frame loss measurement frame, measures the number of data frames being transmitted and writes this number in the data frame loss measurement frame. The MEP on the receiving side measures the number of received data frames and writes this number in the data frame loss measurement frame. By then subtracting the number of data frames received by the MIP from the number of data frames transmitted by the MEP on the transmitting side, the data frame loss between the MEP on the transmitting side and the MIP is measured. Further more, by subtracting the number of data frames received by the MEP on the receiving side from the number of data frames transmitted by the MIP, the data frame loss between the MEP and the MEP on the receiving side is measured. However, no consideration is given to the existence of link aggregation between the MEP on the transmitting side and the MIP, and neither is any consideration given to the existence of link aggregation between the MIP and the MEP on the receiving side.
In Japanese Unexamined Patent Application, First Publication (JP-A) No. 2008-131615, consideration is given to the existence of link aggregation between the pair of communication devices. In addition, by transferring an OAM frame in all of the links from the MEP on the transmitting side to the MEP on the receiving side, it is possible to detect which of the links between the MEP on the transmitting side and the MEP on the receiving side an obstruction has occurred in. However, no consideration is given to measuring the data frame loss between the MEP on the transmitting side and the MEP on the receiving side.